Development of micro controller-based monitoring system for a stand-alone photovoltaic system

Photovoltaic (PV) system performance highly depends on meteorological parameters and, to reduce frequent maintenance and avoid PV system failure, the meteorological and electrical parameters of the system need to be monitored. This paper is on the development of a  simple, reliable and high precision photovoltaic monitoring system, which obtains PV system parameters (i.e. PV panel temperature, irradiance, PV battery voltage, ambient temperature and humidity and PV system load current) in real time, display and store the parameters in personal computer. The system uses electronic sensors to obtain the PV system parameters, which are then processed by a microcontroller with Arduino Board and the parameters displayed in personal computer. C language was used for the microcontroller programming. From the experimental results obtained from the work, it shows that the parameters obtained using the developed systems have good correlations with those obtained using standard commercial instruments used in meteorological stations and laboratory for measurements of the same parameters. The mean bias error of the parameters obtained using the developed system to those obtained using meteorological/laboratory instruments are 0.043%, 0.0412%,-0.297% and 0.024% for solar radiation intensity, temperature, humidity and PV battery voltage measurements respectively. The research would provide PV end-users with important information that will be useful in improving PV system performance by reducing frequency of maintenance and also avoid PV system failure.  http://dx.doi.org/10.4314/njt.v35i4.2

Hygrothermal performance of building envelopes in the tropics under operative conditions : condensation and mould growth risk appraisal

Poor indoor hygrothermal performance increases the risk of indoor moisture problems and deterioration due to mould growth, corrosion and damage to archival materials. Hence, proper control of indoor thermohygric intensity abates indoor moisture and its associated problems. This paper presents the results of envelopes hygrothermal performance assessments in a hot and humid climate building with varying operational profile between adjacent spaces. The case-studied building runs on 24hrs cooling mode in one part against natural and/or mechanical supply-exhaust fan means on the other. In-situ experiments were combined with hygrothermal analytical methods to assess the envelope thermal quality together with the operative conditions against condensation and mould growth risks. The results show that the building is overcooled leading to poor envelope hygrothermal performance with associated condensation and mould growth problems on non-airconditioned sides of the envelopes

Assessment of Physico-chemical and Microbiological qualities of Abattoir Wastewater in Sokoto, Nigeria

Wastewater samples were collected from three different points in Sokoto (Nigeria) abattoir and the physico-chemical and the microbiological qualities were determined. The pH of the wastewater was near neutral in the range of 7.22-7.47. The physico-chemical parameters were biochemical oxygen demand (BOD) (31.4mg/l), dissolved oxygen (DO) (85.0mg/l), and chemical oxygen demand (COD) (3.20mg/l). The microorganisms identified, mostly pathogenic, included<i> Escherichia coli, Salmonellatyphi, Neisseria lactamica, Klebsiella pneumoniae, Serratia marcescens, Branhamella catarrhalis, and Shigella sp, Aspergillus clavatus, Aspergillus flavus, Aspergillus niger, Curvularia sp, Trichophyton rubrum, and Penicillium echinulatum. </i>The potential public health implications associated with discharging untreated abattoir wastewater into the environment and thus, the need for adequate treatment to ensure decontamination as well as providing wastewater treatment facility in the abattoir are discussed.Keywords: Assessment, Physicochemical, Microbiological, Abattoir, Wastewate

Assessment of the efficiency of a yeast biofilter in the treatment of abattoir wastewater

A yeast biofilter consisting of Candida krusei, Candida morbosa, Torulopsis dattila, Torulopsis glabrata, and Saccharomyces chevalieri was constructed to bioremediate abattoir wastewater. Potato peels were used as filter bed for the growth of the yeasts. Wastewater samples were collected from three different points in Sokoto (Nigeria) abattoir and the physiochemical as well as the microbiological qualities of the wastewater were determined before and after biofiltration. The results revealed that after the biofiltration process, the pH, biochemical oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), and the nitrate content of the wastewater were drastically reduced. Similarly, there was a decrease in the variety of microorganisms isolated as well as in microbial counts after the biofiltration process. Salmonella typhi, Neisseria lactamica, Serratia marcescens, Branhamella catarrhalis, Shigella sp, Penicillium sp, Curvularia sp, and Trichophyton rubrum were completely eliminated after the biofiltration process. The reduction in the pH, BOD, DO, COD, nitrate as well as in the variety and total counts of bacteria and fungi for the wastewater after the biofiltration process indicated that the biofilter was effective in bioremediation of the wastewater. The percentage efficiency of the biofilter was found to be 42.5%.Key words: Assessment, efficiency, yeast, biofilter, abattoir, wastewater

Sero-Prevalence of Cytomegalo Virus Antibodies in Pregnant Women Attending Two Selected Hospitals in Sokoto State, North-Western Nigeria

Infection with cytomegalo virus (CMV), especially in pregnancy may cause pregnancy complications such as congenital infection, non-hereditary deafness, intrauterine growth restriction and other high defects. This study was to evaluate the prevalence of CMV in pregnant women attending Antenatal Clinics at Maryam Abacha Women and Children Hospital (MAWCH) and Sokoto Specialist Hospital (SSH). The study enrolled 90 pregnant women (age range: 16-45 years old) and data on demographic and life styles obtained using structured questionnaire. Serum samples were assayed using CMV Ig-G EIA kit. Out of the 90 pregnant women examined, 88(97.8%) had IgG protective antibodies to CMV while 2(2.2%) did not have protective antibodies. The prevalence rate of 2.20% was obtained in pregnant women that did not have the protective CMV IgG antibodies and were in the age range of 16-30 years old. They were also found to be in their second trimester, which could have increased the risk of intrauterine transmission. The risk factors for CMV were observed to have been significantly (P > 0.05) correlated with the socioeconomic status, the levels of CMV Ig-G antibodies, stage of pregnancy as well as the symptoms of pregnancy complications observed in the study population while they were insignificant (P < 0.05) in the case of number of previous pregnancies. The outcome of effects on the fetus was usually fatal and irreversible. Therefore, all pregnant women should scrupulously consistently adhere to routine infection control precautions. Keywords: Cytomegalo virus, Pregnant women, sero-prevalence, Sokoto

Determination of the antimicrobial susceptibility pattern of extended spectrum beta lactamase (esbl) producing and the non-esbl producing strains of Escherichia coli

Background: The extended spectrum beta lactamases producing bacteria are bacteria of great concern among Gram negative bacilli. Escherichia coli stand out as major carrier of this enzyme. The appropriate control of this resistance pattern depends on using the antimicrobial regimen of best choice. Therefore the value of the susceptibility profile of organism harboring this enzyme cannot be overemphasized.Objectives: To determine the antimicrobial susceptibility of extended spectrum beta lactamases (ESBL) producing and the non-ESBL producing strains of Escherichia coli from clinical isolates of Escherichia coli in University of Maiduguri Teaching Hospital.Methodology: Confirmed variants of Escherichia coli were screened and confirmed for ESBL possession. Subsequently, modified Kirby Bauer method was utilized to test for antibiotic susceptibility using the commercially available Oxoid single disc for some major antibiotics.Results: A total of 172 strains of Escherichia coli were identified during the study period. Out of this number; 131 were identified as ESBL positive while a total of 41 were ESBL negative. The highest sensitivity for both the ESBL positive and ESBL negative strains of Escherichia coli was observed with Imipenem followed closely by Gentamicin.Conclusion: The study reveals narrow choice of antibiotics for the ESBL positive isolates of Escherichia coli although Imipenem antibiotic still retains its sensitivity.Keywords: Cephalosporins, Resistance, Maiduguri, Nigeri

Biochemical properties of Paracoccus denitrificans FnrP:Reactions with molecular oxygen and nitric oxide

In Paracoccus denitrificans, three CRP/FNR family regulatory proteins, NarR, NnrR and FnrP, control the switch between aerobic and anaerobic (denitrification) respiration. FnrP is a [4Fe-4S] cluster containing homologue of the archetypal O2 sensor FNR from E. coli and accordingly regulates genes encoding aerobic and anaerobic respiratory enzymes in response to O2, and also NO, availability. Here we show that FnrP undergoes O2-driven [4Fe-4S] to [2Fe-2S] cluster conversion that involves up to 2 O2 per cluster, with significant oxidation of released cluster sulfide to sulfane observed at higher O2 concentrations. The rate of the cluster reaction was found to be ~6-fold lower than that of E. coli FNR, suggesting that FnrP can remain transcriptionally active under microaerobic conditions. This is consistent with a role for FnrP in activating expression of the high O2 affinity cytochrome c oxidase under microaerobic conditions. Cluster conversion resulted in dissociation of the transcriptionally active FnrP dimer into monomers. Therefore, along with E. coli FNR, FnrP belongs to the subset of FNR proteins in which cluster type is correlated with association state. Interestingly, two key charged residues, Arg140 and Asp154, that have been shown to play key roles in the monomer-dimer equilibrium in E. coli FNR are not conserved in FnrP, indicating that different protomer interactions are important for this equilibrium. Finally, the FnrP [4Fe-4S] cluster is shown to undergo reaction with multiple NO molecules, resulting in iron nitrosyl species and dissociation into monomers

A cardinal role for cathepsin D in co-ordinating the host-mediated apoptosis of macrophages and killing of pneumococci

The bactericidal function of macrophages against pneumococci is enhanced by their apoptotic demise, which is controlled by the anti-apoptotic protein Mcl-1. Here, we show that lysosomal membrane permeabilization (LMP) and cytosolic translocation of activated cathepsin D occur prior to activation of a mitochondrial pathway of macrophage apoptosis. Pharmacological inhibition or knockout of cathepsin D during pneumococcal infection blocked macrophage apoptosis. As a result of cathepsin D activation, Mcl-1 interacted with its ubiquitin ligase Mule and expression declined. Inhibition of cathepsin D had no effect on early bacterial killing but inhibited the late phase of apoptosis-associated killing of pneumococci in vitro. Mice bearing a cathepsin D-/- hematopoietic system demonstrated reduced macrophage apoptosis in vivo, with decreased clearance of pneumococci and enhanced recruitment of neutrophils to control pulmonary infection. These findings establish an unexpected role for a cathepsin D-mediated lysosomal pathway of apoptosis in pulmonary host defense and underscore the importance of apoptosis-associated microbial killing to macrophage function

Can bile duct injuries be prevented? "A new technique in laparoscopic cholecystectomy"

BACKGROUND: Over the last decade, laparoscopic cholecystectomy has gained worldwide acceptance and considered to be as "gold standard" in the surgical management of symptomatic cholecystolithiasis. However, the incidence of bile duct injury in laparoscopic cholecystectomy is still two times greater compared to classic open surgery. The development of bile duct injury may result in biliary cirrhosis and increase in mortality rates. The mostly blamed causitive factor is the misidentification of the anatomy, especially by a surgeon who is at the beginning of his learning curve. Biliary tree injuries may be decreased by direct coloration of the cystic duct, ductus choledochus and even the gall bladder. METHODS: gall bladder fundus was punctured by Veress needle and all the bile was aspirated. The same amount of fifty percent methylene blue diluted by saline solution was injected into the gall bladder for coloration of biliary tree. The dissection of Calot triangle was much more safely performed after obtention of coloration of the gall bladder, cystic duct and choledocus. RESULTS: Between October 2003 and December 2004, overall 46 patients (of which 9 males) with a mean age of 47 (between 24 and 74) underwent laparoscopic cholecystectomy with methylene blue injection technique. The diagnosis of chronic cholecystitis (the thickness of the gall bladder wall was normal) confirmed by pre-operative abdominal ultrasonography in all patients. The diameters of the stones were greater than 1 centimeter in 32 patients and calcula of various sizes being smaller than 1 cm. were documented in 13 cases. One patient was operated for gall bladder polyp (our first case). Successful coloration of the gall bladder, cystic duct and ductus choledochus was possible in 43 patients, whereas only the gall bladder and proximal cystic duct were visualised in 3 cases. In these cases, ductus choledochus visibility was not possible. None of the patients developed bile duct injury. CONCLUSION: The number of bile duct injuries related to anatomic misidentification can be decreased and even vanished by using intraoperative methylene blue injection technique into the gall bladder fundus intraoperatively